OpinionColumnistsLeonard Levitt By LEN LEVITT @LenLevitt Bill de Blasio's police missteps New York City Mayor Bill de Blasio attends St. Patrick's Day Mass at St. Patrick's Cathedral on March 17, 2014. New York City Mayor Bill De Blasio not march in the parade because organizers refuse to let participants carry pro-gay signs. Photo Credit: Charles Eckert Updated March 17, 2014 2:11 PM Print Share fbShare Tweet Email Every time Mayor Bill de Blasio says or does something involving the NYPD, he seems to trip over himself. First, there was his ill-considered telephone call to a deputy chief to check on the arrest status of campaign supporter Bishop Orlando Findlayter. Then, after a speech detailing his citywide initiative to curb traffic fatalities, his motorcade was caught blowing through a couple of stop signs. Last week, the mayor pointed to statistics that showed that since taking office 10 weeks ago, the number of murders had fallen 21 percent and shootings had dropped 14 percent compared with the same period a year ago. The reason for the declines, he said: the de Blasio approach to policing. However, you can't conclude anything with certainty on a scant 10 weeks of data. "The usual rule in social science is you have at least one year's data to draw any conclusions," says the NYPD's unofficial official historian, Thomas Reppetto. "You can't just go from month to month because things will change and the good narrative will be used against you as a bad narrative." Moreover, those 10 weeks occurred during one of the city's most bitter winters. That's when crime drops. Criminals, like everyone else, don't like to go out in the cold. By LEN LEVITT @LenLevitt Len Levitt is the author of “NYPD Confidential: Power and Corruption in the Country's Greatest Police Force." Share on Facebook Share on Twitter Comments We're revamping our Comments section. Learn more and share your input.